The effect of cold cap boundary conditions on the flow field was investigated in a cavity with Joule-heating flow. This cavity has dimension of 100mm×100mm×100mm with a top plate whose condition can be changed as fully or partly cooling as 50%, 75% of the top wall because the cold cap is modeled. Top cooling wall is kept at 20°C, and all other walls are under adiabatic condition. The working fluid is a glycerin-water solution with electrolyte. The Joule-heating cavity is accomplished by passing an alternative current employing a pair of plate electrodes immersed on a facing plane of the liquid in order to generate internal heat source by connecting them with a constant voltage (65V). The electrode surfaces are assumed to be iso-potential and the rest of the boundaries are treated as electrically and thermally insulated. Test section is located in the middle plane between two electrodes. Two-dimensional velocity distribution is visualized by Particle Image Velocimetry (PIV), and one-dimensional continuous velocity profiles are observed by Ultrasonic Velocity Profiler (UVP). UVP method is well applicable for time-dependent velocity, especially for unstable flow measurement. As a result, it is revealed that cold cap boundary conditions affect the flow field in the whole cavity. In case of full cooling on the top wall, the flow behavior is unstable by multi-vortex inside the cavity. However, the main vortex has a diameter of about 90mm in both cases of 50% cooling and 75% cooling. Besides, when the top wall is cooled of 50%, the center of the vortex is fixed. Meanwhile, in case of cooling the 75%, the variation of the center of the vortex is moving. This is concluded that the influence of spatial disturbances by side walls is large. These characteristics were also confirmed using a Computational Fluid Dynamic, named GSMAC-Finite Element Method that combined three fields: Flow field, Thermal field and electromagnetic field.
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